


DoomTale

by Eytanium



Category: Doom (Video Games), Undertale (Video Game)
Genre: Other
Language: English
Status: In-Progress
Published: 2019-09-09
Updated: 2020-05-09
Packaged: 2020-10-13 01:16:31
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 3,843
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20574068
Author URL: https://archiveofourown.org/users/Eytanium/pseuds/Eytanium
Summary: DOOM and Undertale Crossover. Originally from by My Cousin, Nixiliium. I know only what he told me about Doom. I know only about Undertale.





	1. Chapter 1

**Author's Note:**

> I was talking to my Cousin and he told me about an old Fanfic that he lost interest in, but I decided to continue it. For the sake of this story, Frisk is a Male and Chara is a Girl. Chara also is a living being. And as Requested by my Cousin, the original Author, the Doom Marine is going to be called Nix.

Once a long time ago, Humans, Monsters, and Demons lived in Harmony. Then humans and Monsters waged war with the Demons, They Fled underground and was never seen by either of the two races again. After the war, the Monsters and Humans lived peace. But it didn't last, another war broke out between the two races. Monsters were driven underground by the humans and the Mages created the barrier to keep the Monsters from reaching the surface again. But, humans also drove one of their kind underground with the Monsters.

Mt. Ebbot 20XX

Humans only told of the Monster and Human War, but only briefly or as a story to get children to behave. But, few children go to Mt. Ebbot and don't return. One day, a young boy was determined to find out about the stories or the truth behind the legends. He tripped over a root and fell into the underground.

The child awakens to find himself on what seemed to be a bed of buttercups. He rubbed his head with a groan. "Ow. My head... What Happened?" He asked the darkness of the room. He looked around the cavern to find the place was empty except for the flowers. The child looked up to the ceiling of the cavern to find a giant hole that led to the surface. "I must have fallen through that hole." He said as he looked around as a voice rang out from the other side of the cavern.

"Hey!"

His attention was immediately caught by the voice. "Who's there? Where are you? Come out, You Coward?!" He shouted, trying to seem intimidating. The voice laughed as he began to freeze up slightly. "Strong words for a scared human." He watched as a human in a green and yellow striped sweater walked in from the dark door. The boy scrambled to his feet in a panic. "Who are you? How did you get here?!" The boy in a blue and Purple striped sweater asked as his voice bounced off the walls of the dark cavern. The girl rolled her crimson eyes as she approached the boy. "Same way you did. Through the hole, but that's not important right now. Follow me, I know a safe place." She said as she reached to grab the boy. He quickly backed out of her reach. "No thanks. I don't want to go with you." He said as he backed up. She gave him a sinister look as she shrugged. "Suit yourself, human." She said as she walked back into the dark side of the room.

'What was that about?' The boy thought as another voice rang out. "Hey! Human! Down here!" He looked down to find what seemed to be a talking buttercup. He looked around before looking at the flower again. "Hi?" The boy said as the flower smiled. "Howdy! I'm Flowey! Flowey the Flower!" The buttercup replied in a chipper voice.


	2. Chapter 2

**Summary for the Chapter:**

> Frisk meets Flowey. And an unexpected friend.

"Howdy! I'm Flowey. Flowey the Flower!" The buttercup said in a chipper voice. The boy was slightly put off by this unusual creature but quietly listened to them. He could feel them observing them. "Hmm...You're new to the underground, aren'tcha?" Flowey said as he gave the boy a look over. He nodded, still put off by the strangely kind flower. "Golly, you must be so confused." Flowey cooed as he motioned the child to approach. "Someone ought to teach you how things work around here!" Flowey said as the human shook slightly. "I guess little old me will have to do," Flowey said as he looked at the child almost hungrily. "Ready?" Flowey asked and before Frisk could do anything, Flowey responded with a, "Here we go!"

Frisk could feel a pull from their chest as a red heart floated out of them and into the area between Flowey and Frisk. Flowey smiled at the sight of the heart. "See that heart? That's your Soul, the very culmination of your being!" Flowey said as Frisk began to practice moving the heart around. "Your Soul starts off weak but can grow strong if you gain a lot of LV." Flowey said as Frisk started to tune in more to what the flower was saying. "What's LV stand for? Why, LOVE, of course!" Flowey said as Frisk seemed to pick up on the abbreviation. "You want some LOVE, don't you?" Flowey asked as Frisk quickly began to shake their head. Flowey, of course, doesn't bother to listen to Frisk. "Don't worry. I'll share some with you!" Flowey said as he gave a winky silly face.

A few seed-like pellets seemed to appear around Flowey as he continued to speak. "Down here, LOVE is shared through..." Frisk noticed his hesitation. "Little white...'friendliness pellets.'" Frisk has a funny feeling that he shouldn't touch those. "Are you ready? Move around! Get as many as you can!" Flowey said as he willed the pellets to approach Frisk's soul. But Frisk was able to move the heart out of the way in time. Flowey's chipper music seemed to die down.

"Hey buddy, you missed them." Flowey said as he conjured up some more pellets. "Let's try again, okay?" And with that, the pellets raced back toward Frisk, but the child, once again, moved out of the way. This time, the bullets hitting what Frisk never thought they would see. A Giant Coffin. The pellets hit the coffin with a loud slam, but the door didn't break. Flowey seemed made at the human kid. "Are you brain dead? Run into the Bullets!" Flowey yelled as he conjured up more pellets.

SLAM!

Flowey gasped as Frisk whirled around to see that the door of the coffin had been kicked...out. 'SOMEONE WAS ALIVE IN THAT THING?!' Frisk thought as the dust settled and out stepped what Frisk can assume is a man. He was tall, probably about 7" maybe even taller. He had on armor and a helmet. The armor and helmet were greenish in color. The man stood there for a minute before looking around. "Dangit." Frisk heard Flowey mutter unhappily as he sunk into the ground. Frisk stared at the tall man in fear as they began to make their way toward them. Frisk held their breath as the man was practically leaning over them. They closed their eyes, waiting for the fated hit. Instead, he heard some words he never would have expected this guy to say. "Where is everyone?"


	3. Chapter 3

**Summary for the Chapter:**

> Introducing our new friend.

**Notes for the Chapter:**

> My cousin and I were talking and decided that Doom Guy's weapon will be changed to a Sword, instead of a pistol. The reason being is that Doom Guy was trapped with the monsters and that his weapon should be different from modern-day weapons. And the sword may become an important aspect of the story. Sorry for any confusion.

Frisk blinked before realizing the man was talking to him. "W-What do you mean by 'Where is Everyone'?" The boy asked as the armored male sighed. "Where are the monsters? The Army? Everyone?" He said as Frisk tilted his head. The man sighed again as Frisk shrugged. "I don't know where anyone is." He said as the armored man turned to look at his surroundings. Frisk silently observed the man. Tall, Strong-looking, Intimidating...No wonder Flowey left in a hurry. Frisk opened his mouth to ask a question, only to be cut off by another voice.

"Hey."

The voice caught the attention of Frisk and the man. Standing in the doorway was the same girl from before. "Looks like Flowey didn't get you. Shame." She said before eyeing the taller male. He glared at her before making a mad dash for her, leaving a cloud of dust behind him. The girl seemed to recognize the man or at least his intention because she turned tail and zoomed out of the doorway as the man closed in on her. Frisk, of course, quickly followed after the man. The girl seemed to make it through the puzzles with ease, but the man simply charged through them with no problem causing Frisk to be left behind. After getting past the puzzles, Frisk quickly caught up with the duo...he wasn't expecting what he found.

Standing in the middle of the hallway, was the mystery man, the girl, and a...large...goat?...woman. The girl simply charged behind the woman as the male was closing in on her. The Goat woman was confused by the girl's actions until she noticed the male and he seemed to notice her. "Toriel?" He spoke as he lowered his weapon, which seemed to be a...sword. The women's glare soften when she realized who he was. "Nix?" She whispered as the man sheathed the sword. After a moment, the woman, Toriel, seemed to charge at the male. He stepped back in alarm before the woman pulled him into a hug.

They stayed in the hug for a few minutes before pulling away. "It's good to see you again, Nix," Toriel said as she held the man's hands. "Same here, Tori." He said as he glared down at the child that hid behind Toriel. "And who is that?" Nix snarled in distaste in the direction of the girl. Toriel smiled before gesturing to the girl. "This is Chara. She is my adopted child." Toriel said in a happy, motherly tone. Nix seemed to snarl at Chara as Chara glared back with her crimson eyes. Frisk, finally, walked up to the group and seemed to clear his throat. Toriel and Nix looked down at him and Toriel quickly gave him a motherly smile. "Hello, my child. I am Toriel, Caretaker of the Ruins. And you are?" She said as Nix looked at Frisk with a somewhat caring look...or at least as much as he could with a helmet on.

"I'm Frisk." He said as Toriel shook his hand. "Nice to meet you, Frisk," Toriel said as she straightened. Frisk seemed to notice that Chara was starting to back out of the room, only for Nix to quickly glare at them, however, this didn't seem to stop her as she sprinted out of the room. Nix quickly sprinted after her, leaving Toriel and Frisk in the dust. Toriel stared in shock at her old friend's speed. She let out a nervous laugh as she looked at Frisk and offered him a hand. "Let's hurry after them before they get into some trouble." She said in a kind tone as Frisk took her hand and they followed after the two. 

Nix was not happy...not at all. The first thing he sees after hundreds of years of sleep is a demon....no...a demon pretending to be a child of his old friend. He was not letting this...thing...hurt Toriel or anyone else if he had a say in it...especially now that a human child was involved. He sped up and reached out to grab the kid by the back of their green and yellow sweater, only for them to take a hard left, out of the way of his grabbing hand. Nix silently cursed as he quickly slid to follow after the...thing. They seemed to run into what seemed to be Toriel's home. The demon went to close the door, only for Nix to bash it in with his shoulder causing the girl to jump back in shock and fear. Nix growled as the...demon backed themselves into a corner. "Nowhere to go now, you filthy little-" "Nix! Chara! You seemed to have found your way to the house." Toriel interrupted as she and Frisk walked inside.

Nix forced himself to turn to Toriel, but still making it so that the little...thing couldn't escape. "Yes. It's a nice home, Tori." Nix said as Toriel smiled and released Firsk's hand. "I'll be in the kitchen making dinner. You play nice, kids." Toriel said as she made her way to the doorway before looking back at the trio. "And Nix?" She said catching the man's attention. "Play nice," Toriel said with a deadpan expression. He nodded as she left through the doorway. After a second, Nix turned and grabbed the nearly escaped demon. He hoisted her up by the front of her sweater. He slammed her into the wall as he glared at her.

"And where do you think you're going?" He snarled as he pushed her further into the wall. He heard a noise from behind him but ignored it. Chara let out a small whimper as Nix pulled his arm back and rammed his hand full forced into the demon's face. A scream from behind him seemed to bring Nix back to his senses. He quickly turned to find that Frisk was standing by the door, with his hands covering his nose, blood dripping at a steady pace from his face. Nix quickly pushed himself away from the demon, dropping her in the process, and rushing to Frisk's side. "Frisk, are you alright?! Let me see your nose." He said as he gently took their hands from the child's face. A bruise was forming over the bridge of the child's nose...broken. Blood was now dripping from their nose and stained the front of their blue and purple sweater. Nix took a deep breath and took Frisk by the shoulders. "Frisk, I'm gonna help you, but it's gonna hurt but only for a bit. Alright?" Nix said in a calm voice. Frisk nodded as he looked at Nix with Determination. Nix moved his hands to the child's nose and held it firmly causing Frisk to whimper. "Hold on for a few minutes. It's alright." Nix said as he got ready. "On the Count of Three. Ready?" Nix said as Frisk nodded. "One...Two...Three!"

SNAP!

Frisk grunted in pain as his nose was popped into place. Nix took him by the shoulders and checked him over again. After he was satisfied with the check. He patted Frisk on the head and smiled. "Good job." He said as he turned to look at Chara, who had a smug shit-eating grin on her face. Nix growled and glared at Chara. "This isn't over, Demon," Nix said as he led Frisk toward the doorway that Toriel went through. He heard a giggle. "I know it's not...It's only the beginning."


	4. Chapter 4

Nix didn't know how to feel, that...thing knew that he couldn't hurt her and He hated it. Frisk's safety is all that matters and that demon is in the way. He can't hurt her without hurting the human kid. He should at least be lucky it was only a broken nose...and that Tori was in the next room. If she saw him hitting the damned demon, she would never forgive him. Nix looked down at the child as he led him to the table. "Are you alright, Frisk?" Nix asked with genuine concern. Frisk nodded as he sat down at the table. Nix gave the child a smile before heading to the kitchen to find his old friend. Tori was getting what smelled like Butterscotch-Cinnamon pie out of the oven. Nix smiled at the fresh smell. Boy, did he miss the old days...

Toriel turned almost running into the armored male. "Oh. Hello, Nix. How are things?" Nix let out a sigh before responding to his long-time friend. "You know how things have been, Tori." Toriel gave him a sad smile. "It has been a while, hasn't it?" Nix let out a grunt of approval. Nix moved to the side to let Toriel through the doorway. Toriel ducked through the door and made her way to the table. The damn demon sat there, smirking, While Frisk gave to duo a smile. Toriel sat the pie on the table before turning back toward the kitchen while Nix took a seat between Frisk and Chara. As soon as the giant goat woman ducked back into the kitchen, Nix's anger began to bubble.

"Aww~. Is the big bad Doom Guy getting angry at little old me?~" Chara cooed teasingly. Nix let out a growl at the little demon bitch. He leaned toward her slightly before hissing. "And if little red riding hood wants to keep her fucking hands, she better be leaving." He hissed before he notices Toriel making her way back into the room. He sits back up and watches as Toriel pours them a cup of tea. Nix stood and began to help serve the pie, purposely giving the bigger pieces to Toriel and Frisk while giving Chara the smallest.

After a moment of silence, Toriel spoke up. "How've things been, Nix?" Catching the attention of the child, demon, and Doom Guy. "Things certainly have changed from when I was last out and about. How has Asgore? Last I heard, you both had a son....Asriel, right?" Nix asked as Toriel frowned at him. "Asgore and I are no longer together and....we did have a son. I would rather not talk about it." Nix quickly backed off the subject and began to talk about....snails. Chara and Frisk would pipe in every once and a while. After Frisk and Chara have been excused, Nix helped Tori clean up. They stood shoulder to shoulder washing dishes in pure silence. After a second, Nix heard Toriel speak. "Nix, I know Frisk is probably going to want to leave soon." She said as Nix dried off his hands and he began to make his way to the door.

"I want you to make me a promise." Nix heard his friend say. "When Frisk leaves, go with him. Keep him safe. Protect him. I want you to promise me that you'll protect Frisk and that you'll get him back to the surface. Don't let Asgore take his Soul. Will you promise me this, Nix?" Nix remained silent for a few minutes. 

"I promise, Toriel."


	5. Chapter 5

**Summary for the Chapter:**

> Toriel was right about Frisk wanting to leave.

**Notes for the Chapter:**

> Sorry for the slow updates. I've been trying to work on other stories and quarantine is driving me crazy. During my time with writer's block I was in a wreck, so I had plenty of time to figure out what happens next. (Not really)

'I promise, Toriel.'

He couldn't get the promise out of his head. Frisk was just a kid and if Toriel wants someone like Nix protecting him then thing must have definitely changed since the war. He remembered being able to walk through the underground when they were first driven down here. But since Asgore, Toriel, and any monster alive during the war feared his strength they locked him away, He understood their fear.

Nix peeked his head into Frisk's room. The boy was fast asleep. Nix felt his heart soften. It's been a while since he checked in on someone else. Nix quietly walked into the room and closed the door behind him. He sat on a nearby chair and observed the room. A child's playroom. Last time, he saw one of these was when Tori and Asgore told him that they were expecting a child. Nix, of course, helped them set up a nursery/playroom for the baby. That's when he learned the Dreemurr's feared his strength when he accidentally broke a desk in anger. Nix looked at the child before settling into his seat. He wasn't sure if he was ready to face any monsters that was still alive from the war. He closed his eyes and slowly fell asleep.

He woke to rustling, Frisk must be ready to leaving. Nix got up as Frisk left the room. He silently followed the child to the stairs before they noticed him. Frisk seemed confused before realizing Nix's intentions. The Doom guy stood by the stairs as he watched the child retreat into the next room, where Tori was reading. A moment passed before Toriel rushed out of the living room and down the stairs, seemingly ignoring Nix. He didn't blame her, she must be trying to focus on proving to Frisk that he couldn't leave. Frisk came sprinting after Toriel and followed her down the stairs, Nix followed after them. He listened to Toriel warn Frisk, but the child seemed Determined to leave the ruins. Frisk spared Toriel even when Tori was attacking him. Finally, Toriel spared Frisk. Nix watched as they exchanged hugs. Toriel walked past Nix while giving him the 'You better keep our promise look'. Nix shuttered. He knew Toriel's fury especially on the battle field. Nix heard Frisk clear their throat and stick his hand out. With a chuckle, Nix grabbed the child's hand and began to walk out of the ruins. It wasn't long until they got to a open room that looks familiar to the room where he met Frisk. And in the middle of the room stood the yellow flower with a smug face. "Clever. Verrrryyy clever." He said with a smirk. "You think you're really smart, don't you?" He asked, but before Frisk could answer the flower continued. "In this world, it's kill or be killed. So you were able to play by your own rules. You spared the life of a single person." The flower looked Nix over before laughing with this deadly look on their face. "Hee hee hee..." He continued to talk. "I bet you feel really great. you didn't kill anybody this time. But what will you do if you meet a relentless killer?" Flower started before looking Nix over again. "Or what if your so-called friend turns on you?" Their attention turned to Frisk. "You'll die and you'll die and you'll die. Until you tire of trying. What will you do then? Will you kill out of frustration? Or will you give up entirely on this world..." He said with a sinister look on his face. "... and let ME inherit the power to control it? I am the prince of this world's future. Don't worry, my little monarch, my plan isn't regicide. This is SO much more interesting." And with that the flower howled with laughter before disappearing into the ground. Frisk was shaking by the time they got to the door. Nix understood. The poor child probably wasn't used to being threatened by a flower. Nix gave their hand a gentle squeeze before pushing the door opened, only to be met with cold wind. Snow. Snow everywhere. Nix led Frisk out the door and shut it behind them. He followed the child through the forest. He also let out a chuckle as Frisk tried to pick up a branch. "Frisk. Hurry up or you'll freeze out here." Nix said, watching Frisk run up beside him. They hear a smash behind them. Nix turned around and glared at the now smashed branch. He took Frisk by the shoulders and began walking him down the path while looking for any threats in the woods. Nix heard crunching snow. He turned to find that no one was there. No footprints or anything. "Let's speed this up, kid." He said pushing Frisk up the path. They got to a Bridge with bar that was wide enough for them to cross though. Nix was about to lead Frisk through the Bridge, but he couldn't move. He felt heavy as if someone was forcing him to stand still. He glanced to Frisk. Seems that the poor kid couldn't move either. Nix heard the crunching of snow. Someone was walking behind them. Nix couldn't move to protect Frisk or himself. He heard a deep baritone voice behind him. "Humans." Frisk tensed up. "Don't you know how to greet a new pal? Turn around and shake my hand." Nix shared a look with Frisk before nodding. They both turned and Frisk took their outstretched hand. *PPPPPFFFFFFFFFFTTTTTTTTTTTTTTTT* What the hell?


End file.
